In vivo study of liposome-modified polyetheretherketone implant on bacteriostasis and osseointegration / 北京大学学报(医学版)

OBJECTIVE@#To develop dexamethasone plus minocycline-loaded liposomes (Dex/Mino liposomes) and apply them to improve bioinert polyetheretherketone (PEEK) surface, which could prevent post-operative bacterial contamination, enhance ossification for physiologic osseointegration, and finally reduce implant failure rates.@*METHODS@#Dex/Mino liposomes were covalently grafted onto the PEEK surface using polydopamine (pDA) coating as a medium. Confocal laser scanning microscopy was used to confirm the binding of fluorescently labeled liposomes onto the PEEK substrate, and a microplate reader was used to semiquantitatively measure the average fluorescence intensity of fluorescently labeled liposome-decorated PEEK surfaces. Moreover, the mouse subcutaneous infection model and the beagle femur implantation model were respectively conducted to verify the bioactivity of Dex/Mino liposome-modified PEEK in vivo, by means of micro computed tomography (micro-CT) and hematoxylin and eosin (HE) staining analysis.@*RESULTS@#The qualitative and quantitative results of fluorescently labeled liposomes showed that, the red fluorescence intensity of the PEEK-pDA-lipo group was stronger than that of the PEEK-NF-lipo group (P < 0.05); the liposomes were successfully and uniformly decorated on the PEEK surfaces due to the pDA coating. After mouse subcutaneous implantation of PEEKs for 24 hours, HE staining results showed that the number of inflammatory cells in the PEEK-Dex/Mino lipo group were lower than that in the inert PEEK group (P < 0.05), indicating a lower degree of infection in the test group. These results suggested that the Mino released from the liposome-functionalized surface provided an effective bacteriostasis in vivo. After beagle femoral implantation of PEEK for 8 weeks, micro-CT results showed that the PEEK-Dex/Mino lipo group newly formed more continuous bone when compared with the inert PEEK group; HE staining results showed that more new bones were formed in the PEEK-Dex/Mino lipo group than in the inert PEEK group, which were firmly bonded to the functionalized PEEK surface and extended along the PEEK interface. These results suggested that the Dex released from the liposome-functionalized surface induced effective bone regeneration in vivo.@*CONCLUSION@#Dex/Mino liposome modification enhanced the bioactivity of inert PEEK, the functionalized PEEK with enhanced antibacterial and osseointegrative capacity has great potential as an orthopedic/dental implant material for clinical application.

Ultrastructure of poly-DL-lactic acid as GTR membrane of soft tissue defects in goats palates / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the ultrastructure changes of PDLLA as GTR membrane of soft tissue defects in the palates of goats.</p><p><b>METHODS</b>To establish penetrating rectangle palate defects in 8 goats. PDLLA membranes were implanted into the defect areas to guide the regeneration of the soft tissue defects. In 1, 2, 4, 6 months after the operation, the membranes were observed with scanning electron microscope.</p><p><b>RESULTS</b>The surface of PDLLA membrane was regular network before implantation. 1 month after the implantation, the edge of network became blunt. 2 months after the implantation, the surface of PDLLA membrane became coarse and irregular. 4 months after the implantation, PDLLA membrane network collapsed. 6 months after the implantation, PDLLA degraded into scraggly accumulation.</p><p><b>CONCLUSION</b>PDLLA membrane supplies good supporting function during concrescence of the soft tissue defects. PDLLA gradually loses mechanic intensity and is absorbed.</p>

Repair of hard cleft palate with absorbable membranes made by poly-DL-lactic acid: a feasibility study / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the feasibility and clinical results of applying poly-DL-lactic acid (PDLLA) biomembranes in cleft palate repair.</p><p><b>METHODS</b>68 cleft palate patients were divided into study group and control group. The traditional surgical method was used to control group to close the soft cleft palate, and the PDLLA biomembrane was used to study group and implanted into the surgical gap between the periosteum and bone at the hard palate, and fixed with suture. The duration, blood loss at operation, post-operative complication, wound healing and recovery were recorded and compared to conventional cleft palate repair.</p><p><b>RESULTS</b>Operations were successfully completed on all 34 patients. Wound healing of soft palate and uvula was uneventful with no incidence of fistula or dehiscence. The primary healing on tissue defect of hard palate occurred in 29 patients, secondary healing occurred in 3 patients, permanent fistula between the oral cavity and the nasal cavity occurred in only one patients, and 3 patients left over fistula on alveolar process. Compared to traditional cleft palate repair, blood loss and incidence of fistula on alveolar process were decreased; the average surgical time was 89.25 minutes and was not prolonged; and there was no significant increase in post-operative complication.</p><p><b>CONCLUSION</b>Hard cleft palate repair with PDLLA biomembranes is safe, simple and practical with good clinical results and is beneficial to minimize the bad influences towards the development and growth for maxilla of cleft palate patients.</p>

Experimental study on the reconstruction of mandibular defects with a new bioactive artificial bone nano-hydroxyapatite/polyamide-66 in dogs / 中华口腔医学杂志

<p><b>OBJECTIVE</b>This study was designed to investigate reconstruction of segmental defect in the mandible using a new bionic materials of nano-hydroxyapatite -polyainides-66 (n-HA/PA66).</p><p><b>METHODS</b>Two defects (15 mm x 10 mm x 5 mm) were created in the mandibular bodies of dogs. One of defects was reconstructed with n-HA/PA66, another not repaired as a blank control. At 2, 4, 8, 12, 16 weeks after operation. Evaluation of effects of n-HA/PA66 on reconstruction of the mandibular defects was carried out by means of radiography and histology.</p><p><b>RESULTS</b>From 2 to 8 weeks after operation, some fiber tissue grew into the space between n-HA/PA66 and mandibular bone. The ossification was observed at 12 weeks post-operation. At 16 weeks, the n-HA/PA66 was connected directly to the mandibular bone by the newborn bone.</p><p><b>CONCLUSIONS</b>The new artificial bone of n-HA/PA66 has the effects of osteoconduction and osteoinduction, with a good biocompatibility and is an ideal bone substitute material for reconstruction of mandibular defect.</p>

Influence of super high molecular weight poly D,L-lactic acid on viability and new bone formation of osteoblasts / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the influence of the viability and new bone formation of osteoblasts by the super high molecular weight poly D,L-lactic acid (SHMW-PDLLA).</p><p><b>METHODS</b>1. The osteoblasts derived from neonatal rat were grown and maintained at steep of SHMW-PDLLA and normal culture medium. The viability and function of the osteoblasts were measured with MTT array. 2. The plate and screws made of SHMW-PDLLA were implanted and fixed at the artificial fractured mandible of dogs. Specimens were gained at 3 and 6 months and examined with macroscopy and SEM.</p><p><b>RESULTS</b>1. There is no significant difference of OD values between the experimental group and the control group (P > 0.05). The SHMW-PDLLA isn't toxic to osteoblast at 1 week and 2 weeks, and the toxicity is 3% at 3 days. 2. There were a lot of new bone formed between the implanted SHMW-PDLLA plate and bone tissues under SEM.</p><p><b>CONCLUSION</b>SHMW-PDLLA hasn't pathological influence on the viability and new bone formation of osteoblasts and it is feasible in tissue engineering of bone.</p>